Fig. 3.

SARS-CoV-2 3CL inhibits RIG-I-like signalling pathways. (A–C) Luciferase activity of lysates from 293T cells transfected with luciferase reporter constructs IFN-b-Luc for 24 h (A), ISRE-Luc (B) or NF-κB-Luc (C), plus Flag-RIG-I-N, Flag-MAVS, Myc-TBK1, Flag-p65, or Flag-IRF3/5D, along with HA-3CL or an empty vector. The results are presented relative to the luciferase activity in control cells expressing the luciferase reporter and empty vector (top). Expression of the indicated transfected plasmids was detected by immunoblotting with an anti-3CL antibody (1:1000) (below). (D–F) Quantitative PCR analysis of IFNB1 (D), IFIT1 (E), and CCL5 (F) mRNA levels in 293T cells transfected for 24 h with the indicated plasmids and HA-3CL or an empty vector (top). The expression of the indicated transfected plasmids was detected by immunoblotting (below). *P < 0.05; **P < 0.001 (unpaired, two-tailed Student’s t-test). Data are representative of at least three independent experiments.